1. Field of the Invention
The present invention relates to a purge apparatus and a purge method of purging an inside of a storage container in which a product is stored, with a purge gas, such as an inert gas or purified dry air.
2. Description of the Related Art
For example, a purge apparatus is known which keeps cleanliness by introducing a purge gas (purging) to the inside of a storage container in which a product, such as a semiconductor wafer or a glass substrate, is stored. In such a purge apparatus, the flow rate of the purge gas supplied to the storage container may be controlled. However, a failure of a control circuit in the purge apparatus or a problem occurred in a supply channel of purge gas may prevent purge gas from being actually supplied into the storage container at a desired flow rate and may result in unsatisfactory purging. There is therefore a demand for determining whether purge gas is suppled into a storage container at a desired flow rate (whether satisfactory purging is being performed).
Japanese Patent No. 4670808 discloses a technique for measuring the flow rate of purge gas supplied to the inside of a storage container. With the measurement container described in Japanese Patent No. 4670808, a dedicated flow rate-measuring unit is placed on the purge apparatus to measure the flow rate of the purge gas supplied from the purge apparatus, so that whether satisfactory purging is performed can be determined. However, it is sometimes desired that whether satisfactory purging is being performed should be determined during a process of actually supplying purge gas to a storage container to be purged.